The present invention relates to a semiconductor device and a method for manufacturing the same, more particularly to a semiconductor device and a method for manufacturing the same which are capable of exactly executing an etch process.
The etch process is one of essential elements in the manufacturing process of semiconductor device and classified into a dry etch process and a wet etch process.
As well known, the dry etch is a technique which etchs a material with a plasma etchant in chamber having an established atmosphere.
On the other hand, the wet etch is a technique which etchs a material with a solution etchant.
So as to explain the dry etch technique, the manufacturing process of conventional multicolored electric field light emitting device (MEFLED) will hereinafter be described in conjunction with FIG. 1a through FIG. 1e.
As shown in FIG. 1a, first, over a transparent substrate 1 is formed a lower transparent electrode 2 with a thickness of about 2000.ANG. and then a first insulation layer 3 is formed with a thickness of 3000.ANG. on the lower transparent electrode 2.
Subsequently, a first color light emitting layer 4 is formed with a thickness of about 6000.ANG. on the first insulation layer 3 and then a photoresist 5 is uniformly coated on the first color light emitting layer 4.
The photoresist 5 is subjected to a selective etch process to form a desired photoresist pattern 5a. It is conventionally called a patterning process that a photoresist pattern 5a is made as above mentioned and then a material is selectively etched using the photoresist pattern as an etch mask.
As shown in FIG. 1b, thereafter, the first color light emitting layer 4 is etched with a reactive ion etch (RIE) method which is a type of the dry etch technique using the photoresist pattern 5a as an etch mask, thereby to form a plurality of first color light emitting layer patterns spaced with an constant interval from each other.
At this time, the surface of the first insulation layer 3 is exposed at portions in which the first color light emitting layer 4 is removed.
As shown in FIG. 1(c), a second color light emitting layer 6 is formed with a thickness of about 6900.ANG. on the exposed surfaces of the first insulation layer 3, the photoresist pattern 5a and the first color light emitting layer pattern 4a.
As shown in FIG. 1(d), subsequently, the second color light emitting layer 6 and the photoresist pattern 5a are subjected to a RIE method using the surface of the first color light emitting layer pattern 4a as an etch-ending point, thereby to form a plurality of second color light emitting layer patterns (6a) between the plurality of first color light emitting layer patterns 4a.
As shown in FIG. 1e, thereafter, a second insulation layer 7 and a conductor are formed on the surfaces of the first color light emitting layer patters 4a and the second color light emitting layer patterns 6a, in this order.
The conductor is then patterned to form a upper electrode having a desired pattern.
Now, the operation of MEFLED shown in FIG. 1e will briefly be described.
The operation of MEFLED is almost similar to that of single colored electric field light emitting device(SEFLED).
As a proper alternating current(AC) voltage is applied to between the lower transparent electrode 2 and the upper electrode 8, electrons are generated at the boundaries between the insulation layers 3, 7 and light emitting patterns 4a,5a.
At this time, the generated electrons are accelerated due to a high electric field which is formed in the light emitting layer patterns 4a,5a serving as a conduction band, thereby becoming hot electrons.
The hot electrons strike lattices in the light emitting layer patterns, thereby ionizing the lattices.
As a result, pairs of electron-holes are generated.
At this time, if the electrons exited to the conduction band are again dropped to a valance band, there is emitted a light which has a wave length corresponding to the energy difference.
Conventionally, a red-colored light conventionally has a wave length of about 6500.ANG. and a green-colored light has a wave length of about 5420.ANG..
However, the above MEFLED has a following problem upon the manufacturing process thereof.
When the first color light emitting layer 4 is dry-etched by the RIE method so as to form the plurality of first color light emitting layer patterns 4a, an ending point for stopping the dry-etching is not exactly detected, thereby causing the surface of first insulation layer 3 which is formed below the first color light emitting layer 4 to unnecessarily be etched.
Therefore, it is impossible to manufacture a reliable MEFLED since the surface of first insulation layer 3 is formed in irregularity.
So as to solve the above problem, the above-mentioned conventional art uses an expensive dry etch apparatus capable of exactly dry-etching to a predetermined ending point or uses an insulation material having an etch selectivity higher than that of first color light emitting layer 4, as the material of first insulation layer 3.
An insulation material having an etching speed slower than that of first color light emitting layer 4 should be used, as the material of first insulation layer 3.
As shown in table 1, that is, there is merely used an insulator such as ZnS in which the etch speed is relatively slow and the etch selectivity is relatively high should be used, as the material of first insulation layer 3.
Conventionally, the process for manufacturing a semiconductor device accompanies different etch processes several times.
Accordingly, an corresponding expensive etch apparatus is used every the execution of each etching process, thereby causing the manufacturing cost to be increased.
As above mentioned, there are disadvantages, in that the conventional art for manufacturing a MEFLED should limitedly use the material of insulation layer and also use an expensive etching apparatus in which an ending point detector is equipped therein.
TABLE 1 ______________________________________ Etch Selectivity Material Etch Rate ZnS etch SrS etch ______________________________________ ZnS(Mn, Sm or Tb) 300 1:1 0.2:1 SrS:Ce 67 4.5:1 1:1 SiON 320 0.9:1 0.2:1 Ta.sub.2 O.sub.5 280 1.5:1 0.3:1 BaTa.sub.2 O.sub.5 23 13:1 3:1 ______________________________________